Medical procedures for the treatment of chronic diseases often require repeated and prolonged access to a patient's vascular system to inject therapeutic compounds and/or to sample or treat the patient's blood. Certain procedures are repeated often enough that it is impractical and dangerous to insert and remove the catheter and the needle from the patient's vein at every session. Many patients are thus fitted with a semi permanent catheter to permit repeated access to the patient's vascular system.
Semi-permanently implanted catheters are generally designed to be as small and thin as possible, to simplify the insertion procedure and to reduce discomfort to the patient. Access to such a catheter is typically provided by one or more ports, which are in fluid connection with the catheter and thus with the patient's vascular system. The port or ports generally have a very thin profile, so they may be implanted in the patient with a minimum of discomfort. In most cases, such a port is implanted subcutaneously, in a pocket formed surgically in the patient's chest or arm so that it lies just under the skin, in a location that is easily accessible to medical personnel. More specifically, a septum of the port is positioned just under the skin so that therapeutic agents may be injected into the port through the skin and through the surface of the septum.
Insertion of therapeutic agents into the catheter is typically carried out by injecting the fluid through the septum of the port, using the needle of a syringe or a similar device. The septum includes at least one surface that is capable of resisting damage cause by multiple piercings from the needle, while re-sealing itself after the needle is withdrawn. The service life of such ports is therefore limited by the durability of the septum. After a certain number of punctures, the septum becomes damaged and is no longer able to re-seal itself. Fluids flowing in the catheter, such as blood, can then leak from the septum necessitating replacement of the port and possibly of the entire catheter. This procedure involves surgically opening the subcutaneous pocket, removing the damaged port from the catheter, and reinserting a new port with an undamaged septum. Replacing the port adds considerable expense, inconvenience and discomfort to the procedure and increases the risk of infections and other complications.